Papillomaviridae and Discovery of new viruses.

Question 1

List two Papillomavirus type most associated with Cervical cancer and Genital warts.

Answer 1

1. Cervical Cancer: HPV-16, -18.
2. Genital Warts: HPV-6, -11.

Question 2

Describe the structure and genome of HPV.

Answer 2

Structure: small, non-enveloped with a icosahedral capsid.
Genome: DS circular DNA genome. Noncoding control region; LCR or URR. Open reading frames; E1-E8, L1 and L2.

Question 3

Describe the replication cycle of HPV.

Question 4

Describe different stages of HPV-associated Cervical Cancer.

Answer 4

Stage 0: Carcinoma in situ. Abnormal cells in the innermost lining of the cervix.
Stage I: Invasive carcinoma that is strictly confined to the cervix.
Stage II: Locoregional spread of the cancer beyond the uterus but not to the pelvic sidewall or the lower third of the vagina.
Stage III: Cancerous spread to the pelvic sidewall or the lower third of the vagina, and/or hydronephrosis or a nonfunctioning kidney that is incident to invasion of the ureter.
Stage IV: Cancerous spread beyond the true pelvis or into the mucosa of the bladder or rectum.

Question 5

Outline the natural history of the changes in viral load, antibody response and cellular immune response during genital HPV infection.

Answer 5

High-risk HPV: clear 12-18 months
Low-risk HPV: clear 4-9 months
*screenshot

Question 6

List two important HPV genes responsible for cellular transformation and and elaborate their potential mechanisms.

Answer 6

1. E6: targets the p53 tumor supression protein to accelerate ubiquitin-mediated degradation. Stimulates telomerase activity.
2. E7: binds to members of the RB family, to distabilize and lose Rb/E2F complexes that repress transcription of genes for cell cycle progression.

Question 7

Describe current diagnostic and therapeutic strategies for the management of HPV-associated cancers.

Answer 7

Diagnostic:
- Serology (ELISA): antibody against L1 using VLP’s not sufficiently sensitive or specific, detect past or current infections.
- Molecular assays: detection of DNA/RNA in cervical swaps or biopsy. (QIAGEN)

Treatment:
- No specific antiviral, interferon/immiquomod for genital warts.

Prevention:
- Quadrivalent vaccine
- GARDASIL
- Cervarix

Question 8

List traditional approaches for virus discovery.

Answer 8

• collect samples w/ disease symptoms
• isolate viruses
• observe virus particles
• identify viral genomes
• clone genomic DNA/RNA

Question 9

What are the advantages of using Next-generation sequencing for virus discovery?

Answer 9

• Many viruses are latent or asymptomatic.
• NGS can identify viral sequences w/o background
  information.
• Viral genomes are assembled de novo w/o ref. sequence.
• NGS has revolutionized virus discovery.